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authorRichard Guo <rguo@postgresql.org>2025-07-08 10:21:44 +0900
committerRichard Guo <rguo@postgresql.org>2025-07-08 10:21:44 +0900
commit55a780e9476a753354a6db887e92125c7886ca6d (patch)
treec91b46c31cef48c02084240d46bc3b44d5e728ba /src/test/modules/commit_ts/sql
parent7376e6085468054328a66e8c10c007bdaaf88f91 (diff)
downloadpostgresql-55a780e9476a753354a6db887e92125c7886ca6d.tar.gz
postgresql-55a780e9476a753354a6db887e92125c7886ca6d.zip
Consider explicit incremental sort for Append and MergeAppend
For an ordered Append or MergeAppend, we need to inject an explicit sort into any subpath that is not already well enough ordered. Currently, only explicit full sorts are considered; incremental sorts are not yet taken into account. In this patch, for subpaths of an ordered Append or MergeAppend, we choose to use explicit incremental sort if it is enabled and there are presorted keys. The rationale is based on the assumption that incremental sort is always faster than full sort when there are presorted keys, a premise that has been applied in various parts of the code. In addition, the current cost model tends to favor incremental sort as being cheaper than full sort in the presence of presorted keys, making it reasonable not to consider full sort in such cases. No backpatch as this could result in plan changes. Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Andrei Lepikhov <lepihov@gmail.com> Reviewed-by: Robert Haas <robertmhaas@gmail.com> Discussion: https://postgr.es/m/CAMbWs4_V7a2enTR+T3pOY_YZ-FU8ZsFYym2swOz4jNMqmSgyuw@mail.gmail.com
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